The fixation of the maxillary and mandibular jaw, also known as the upper and lower dental occlusal arches, is known as intermaxillary fixation or stabilization (“IMF”). IMF is a method used to repair maxillary and mandibular fractures by bringing bone fragments into proper position and alignment. These methods are also applied to the stabilization of single bone fragments.
Wiring techniques represent the earliest methods of securing the maxillary and mandibular jaw. The method involves utilizing metallic wires that are placed around one or more teeth at their base and then twisted using various methods to secure the teeth. The wires can be used in pairs or in greater multiples along the span of the dental arch forming a series, or, alternatively, a single strand of wire may incorporate a plurality of teeth. The methods of placing and twisting the wire so described achieve a secured fixation. The ultimate combination of the aforementioned methods involves the upper and lower arches secured along their respective lengths, and subsequently the maxillary and mandible jaws secured to one another with ligatures, thus accomplishing IMF. Unfortunately, the technique is tedious and time consuming. The wires can also interfere with dental hygiene.
Another conventional technique known to those of skill in the art includes utilizing arch bars in combination with wiring. Specifically, a metal, or sometimes plastic, bar is shaped to approximate the curvature of the maxilla or mandible. Ligatures are wrapped around the teeth and over the bar, and then twisted onto the bar. In a typical embodiment, arch bars have a plurality of hooks or tabs facing in the same direction. If two arch bars are used, the hooks or tabs of each one are placed in opposing directions so that ligatures may securely affix the jaws together. The semi-rigid arch bars span the dental arch providing stability along the upper end of the maxillary or mandible jaw even when a fracture or fractures exist between teeth, while the plurality of hooks allows placement of ligatures between the jaws at varying angles and lengths to allow various combinations of beneficial tension vectors.
Unfortunately, arch bars require significant time to secure in place and tend to interfere with dental hygiene. Another limitation of arch bars is that they may not provide satisfactory fixation in a fully or partially edentulous patient. Furthermore, the wire ligatures themselves are painful and frequently must be adjusted by the treating physician or other medical professional. Finally, removal of the arch bars may be difficult and carries with it the increased risk of dental injury and the need for operative anesthesia.
Another technique known to those of skill in the art involves placing a plurality of screws in the mandible or maxillary jaw between the tooth roots so as to avoid them. The screw head functions to allow ligatures to be wrapped around it and screw heads used may contain holes running continuously through their length enabling the passage of ligatures through the screw heads. Thus, ligatures may be secured to contiguous sets of screws in varying combinations to provide IMF. This technique is limited by an absence of overall structural stability which may be necessary in some instances, e.g., when a patient has fractures around the teeth.
Improving on the technique of placing screws into the bone, another method of securing arch bars involves using the same arch bar method described above, but substituting ligatures with a plurality of arms and attachment loops attached transverse to the longitudinal axis of the arch bar along its length, and placing screws into the bone through openings in the arms or attachment loops. This procedure and the apparatus associated therewith is disclosed in U.S. Pat. No. 8,118,850 (“the '850 patent”) and U.S. Pat. Pub. No. 2011/0152951, the disclosures of which are hereby incorporated by reference herein. Such methods benefit from not having wires interfere with dental hygiene while simultaneously providing a secure connection. However, application of the method results in the arch bar pressing against the gingiva when in use, rendering the gingiva vulnerable to pressure necrosis.
There exists a need for a method utilizing an anchor plate or dental arch bar in an IMF procedure without causing pressure necrosis.